1. Field of the Invention
The present invention relates to driver circuits for driving display devices, and more particularly relates to a driver circuit for supplying gradation voltages corresponding to an input video signal to each of a plurality of data lines formed on a display panel.
2. Background Art
For example, a two-dimensional display panel such as liquid crystal display panels includes a plurality of data lines (source lines) extending in a vertical direction within an in-plane direction of a screen, and a plurality of scan lines (gate lines) extending in a horizontal direction. For example, the display panel is placed on a glass substrate. The display panel on the substrate has, for example, an outer peripheral area, where a driver circuit that is a device for driving the display panel is provided.
The driver circuit generates, on the basis of a video signal input from the outside, gradation voltages corresponding to the luminance level of each pixel in the display panel, and applies the gradation voltages to each of the data lines of the display panel.
For example, Japanese Patent Application Laid-Open No. 2008-292926 discloses liquid crystal driving ICs (10a, 10b) which are connected in cascade and disposed in adjacent to each other. The liquid crystal driving ICs (10a, 10b) have gradation voltage generating circuits (110) each disposed at the center of the ICs. The gradation voltage generation circuits (110) are each provided with gradation voltage equalizing terminals (Qa, Qb, Qc, Qd) for equalizing gradation voltages. The terminals are each connected to their corresponding terminals through a gradation voltage equalization line (Sa) having a linear shape.
Japanese Patent Application Laid-Open No. 2007-37191 discloses a voltage generating circuit, including a first selector of a first conductivity-type, 2a pieces of second selectors of the first conductivity-type, a first selector of a second conductivity-type, and 2a pieces of second selectors of the second conductivity-type. In the voltage generating circuit, the first and second selectors of the first conductivity-type are comprised of MOS transistors, which are parallel in a channel width direction. Among the MOS transistors comprising the second selectors of the first conductivity-type, the MOS transistors connected to the first selector of the first conductivity-type are disposed adjacent to each other in the channel width direction.